1. Field of the Invention
The present invention relates generally to improvements in the design and operation of article handling apparatus and in particular to article handling mechanisms of the type that utilize computer-controlled electromechanical technology, and in the illustrated embodiment a robotically positioned gripper, which uses suction, for example, for grasping and moving a selected article from one area to another, such as from a storage area to a dispensing area.
2. Description of the Prior Art
Most prior art article handling mechanisms, more specifically referred to in the description of the present invention as being in the environment of a point-of-sale (POS) article dispenser, rely on a multitude of motors, switches and solenoids for moving various portions of the handling mechanism, and handling of the articles themselves, such as packaged products. Most such machines require one motor, switch and/or solenoid dedicated for each row, column or type of article or package to be handled or dispensed therefrom. Such machines generally suffer from numerous disadvantages, such as poor reliability due to mechanical failures, as well known by those skilled in this art.
U.S. Pat. No. 5,240,139 represents a significant improvement in article handling devices. It describes the use of a negative air pressure lifter (i.e., article pickup or handling mechanism), which uses suction, i.e., a reduced or so-called “negative” air pressure created by a partial vacuum, for making a secure contact to an article to be retrieved by entering the open top of an article storage bin located in a refrigerated storage area of a vending machine. Although robotic, and specifically suction-type lifting mechanisms are in common use in factory settings, where space limitations are generally relaxed, their use in tight confines, such as an article vending machine, has not gained wide acceptance. Due to the greater reliability and versatility of vending machines of the type which utilizes suction technology for grasping and moving selected articles, it would be desirable to develop new techniques and methods for the operation and control of such machines, as well as for other more generalized article handling mechanisms.
Hose storage is provided in the forenoted U.S. Pat. No. 5,240,139 by use of a longitudinally compressible air hose having about a 3:1 compression ratio. One end of the hose is connected to a source of negative air pressure which is provided to a support beam which is moved laterally over the top of the freezer. The other end of the air hose is connected to an article pickup head. Lateral positioning of a compressible hose is satisfactory in the environment of U.S. Pat. No. 5,240,139 since the freezer compartment only occupies the lower half of the interior of the vending machine, leaving the upper half available for the hose and its positioning mechanism. However, since the significant part of the expense of operating a vending machine business comprises servicing (i.e. filling) of the vending machine with products, it would be desirable to be able to provide taller article storage bins, with or without a freezer compartment, in order to maximize utilization of the article storage volume within the interior of the vending machine cabinet. Prior art article dispensers typically use between 50 and 60 percent of their available height for article storage.
Due to the above noted disadvantage, it would be desirable to decrease the height requirement for the hose positioning mechanism. One such way would be to consider the use of a non compressible hose. A non compressible hose has the advantage that it can be driven and/or guided by direct engagement with the walls of the hose, a much simpler technique as compared to the indirect hose positioning technique of the forenoted U.S. Pat. No. 5,240,139. Additionally, a non compressible hose has the advantage of maintaining a constant length in spite of being subjected to changes in vacuum. Even furthermore, a non compressible hose has greater structural integrity and reduced leakage, as compared with, for example telescopic tubing. However, two serious problems are presented by the use of a non compressible hose: where can a sufficient length of the hose be stored in order that it's free end can travel the distance from the bottom of the hose positioning mechanism (a position aligned with the top of an article storage bin) to the bottom of the article storage bin; and how can it be simply and reliably be withdrawn and retracted to and from the storage area as needed?
PCT patent publication WO 99/12132 entitled VENDING MACHINE discloses a vending machine having a folded articulated arm for positioning an article gripping suction hose into a freezer for retrieving articles to be dispensed. The hose is non-compressible, and continuous from a base area located beneath the articulated arm to its free end, where it is coupled to an article pickup head. A linear actuator and arm mechanism located in the base area is used to drive the hose into and out of the base area, through the articulated arm and into the freezer compartment. The hose positioning arrangement of this PCT patent publication has a similar disadvantage as the forenoted U.S. Pat. No. 5,240,139, in that a significant volume within the vending machine cabinet is required for the mechanism which positions the hose over and into the storage bins during a package dispensing cycle (i.e., a height almost equal to the height of the article storage bins themselves). Additionally, it is noted that only a relatively small length of hose is required to be stored, corresponding to the amount of hose required to move the article pickup head in the Z direction (i.e., into and out of the freezer), since a significant length of the hose is already stored in the folded articulated arm. Even furthermore, it is noted that this patent publication teaches a relatively complex mechanism for hose positioning, storage and drive.
German patent DE 2455673 by G. Lucas, published May 26, 1976 and entitled VENDING MACHINE FOR ICE CREAM-USING SUCTION HEAD TO PICKUP WRAPPED BLOCKS OF ICE CREAM FROM STACK IN REFRIGERATOR discloses an ice cream vending machine wherein a movable carriage is mounted inside a freezer and laterally positionable over the article storage bins. The carriage includes a drive mechanism for lowering an electric cord having a suction motor at its free end into the article storage bins for retrieving the ice cream packages. This type of positioning mechanism for an article handling device avoids the problem of hose storage by actually lowering the suction motor into the bin. It's is particularly disadvantageous since the repeated bending and flexing of the electric cord can lead to reliability/failure problems. Additionally, the diameter of the suction motor places severe limitations upon the dimensions of the article storage bins.
U.S. Pat. No. 5,957,326 entitled APPARATUS FOR RETRIEVING RANDOMLY ORGANIZED ARTICLES, describes a vending apparatus including carriage mounted for being laterally positionable over an article storage bin, and includes a drive mechanism for lowering into the storage bin a pickup head having a plurality of suction cups mounted thereon. Each suction cup is individually connected to a substantial length of hose which leads back to a manifold which supplies suction thereto. This type of positioning mechanism for an article handling device is particularly disadvantageous since the plurality of suction hoses connected to the pickup head are not provided in a hose storage area, and instead are coiled/dragged beneath the carriage during its repositioning thereby protruding significantly into a space which could more advantageously being used for the storage of articles to be vended/dispensed.
U.S. Pat. No. 4,557,659 the entitled DEVICE FOR SUPPORTING AND HANDLING LOADS BY MEANS OF VACUUM OPERATED SUCTION PADS, describes an article lifting and transport device wherein an electric motor slidably mounted along a raised and rotatable I beam, is used to lower an electrical cord towards an article to be handled. The electrical cord has at its free end a pickup head including a plurality of suction cups mounted thereon. A suction providing hose, which is continuous from a suction generator to the pickup head, is loosely supported between its ends by a series of slides connected to the rotatable I beam. This type of positioning mechanism for an article handling device is disadvantageous for substantially the same reason as the forenoted U.S. Pat. No. 5,957,326, due to the fact that the suction hose is dragged alongside and behind the carriage during its repositioning, thereby protruding significantly into a space which could more advantageously being used for the storage of articles to be vended/dispensed.